I observed that there is a strong argument that the photograph constitutes campaigning, particularly because, by the time it hit doormats in the constituency, the election had been called.
Over at the North Antrim Local Interest List, Nevin develops the theme. The letter, which is dated mid March, was not distributed until the 6-8 April. Why the delay? Nevin notes the striking coincidence that Paisley's correspondence is dated from the very day the election was called.
It appears that the letter was not printed on official Commons notepaper, but undoubtedly the portcullis livery which it carries is intended to give the impression that it is distributed by Ian Paisley in his capacity as MP, rather than in his capacity as a supporter of Ian Junior's election campaign.
The sender, however, is given as the DUP's constituency office in North Antrim (9-11 Church Street Ballymena), which is listed, on the party's website, as Ian Junior's office, whereas his father's office is listed as 256 Ravenhill Road.
Two questions remain. Was any public money, in particular Ian Paisley Senior's House of Commons Communications Allowance, expended on this communication? Will the letter and its distribution be included in Ian Paisley Junior's general election budget?